Press Release

Orexigen(R) Therapeutics Releases New Efficacy Data for Contrave(R) in Late Breaker Presentations at the 27th Annual Scientific Meeting of The Obesity Society

SAN DIEGO, October 27, 2009 -- Orexigen® Therapeutics, Inc. (Nasdaq: OREX) today announced results from new intent to treat (ITT) analyses from the COR-I and COR-II Phase 3 trials of Contrave® (naltrexone SR/bupropion SR), the first of two late stage Orexigen candidates for the treatment of obesity. These data expand on top-line results announced in July and complement findings from a panel discussion on Saturday where the Company presented data on Contrave patients who completed 56 weeks of therapy. These ITT data were presented today in two late breaker oral presentations at the 27th Annual Scientific Meeting of The Obesity Society in Washington, D.C.

Results showed that, on an ITT basis,

Approximately 25-33% lost 10% or more of their body weight and 12-16% lost at least 15%; and

Obese patients on Contrave demonstrated significant improvements in important markers of cardiometabolic risk including waist circumference, HDL and triglycerides

“The data presented today and on Saturday provide a deeper view of Contrave, and what we believe is a balanced efficacy and safety profile,” said Eduardo Dunayevich, M.D., Chief Medical Officer of Orexigen. “These findings should help clinicians assess the potential value of Contrave pharmacotherapy in managing obesity and support our belief that if approved, Contrave could meet the broad range of needs of this patient population by virtue of its efficacy, safety and benefits on key markers of cardiometabolic risk.”

Additional data from today’s late breaker presentations are outlined in the below table:

Efficacy Result+

COR-I

COR-II

PBO(N=511)

Contrave32(N=471)

PBO(N=456)

Contrave32(N=702)

Greater than or equal to 10% weight loss (%)

7.4%

24.6%*

5.7%

32.9%*

Greater than or equal to 15% weight loss (%)

2.0%

11.9%*

2.4%

15.7%*

Markers of Cardiometabolic Risk+

COR-I

COR-II

PBO(N=511)

Contrave32(N=471)

PBO(N=456)

Contrave32(N=702)

Waist circumference (cm)

‐2.5

‐6.2*

‐2.1

‐6.7*

Fasting triglycerides (mg/dL)

‐3.5

‐18.1*

‐0.5

‐11.8*

Fasting HDL (mg/dL)

‐0.1

+3.4*

‐0.9

+3.6*

Fasting LDL (mg/dL)

-3.3

-4.4

‐2.1

‐6.2*

hsCRP (mg/L)

-0.4

-1.1*

+0.2

-0.8*

+ Data based on intent-to-treat (ITT) last observation carried forward (LOCF) analyses of all randomized patients who had at least one post-baseline observation while on study drug. *p<.05 for difference between Contrave and placebo

Contrave Obesity Research (COR) Trial Design and Safety Profile

All Phase 3 trials in the COR program were 56 week, randomized, double-blind, placebo-controlled trials. The co-primary endpoints were the proportion of patients achieving at least 5% weight loss and percent change in body weight compared to placebo. Secondary endpoints included multiple measures of cardiometabolic risk, food cravings and eating control, as well as HbA1c in the COR Diabetes trial. Patients were randomized to receive either placebo or Contrave, BID, with a four week titration period.

As previously reported, across the entire COR program, seven serious adverse events were attributed by investigators as possibly related to Contrave treatment. These include cholecystitis (gallbladder inflammation) , seizure, palpitations, paresthesia and vertigo. The most frequently observed treatment-emergent adverse events were nausea, constipation and headache. Nausea was the leading adverse event resulting in discontinuation; however, for the majority of patients experiencing nausea, it was mild to moderate, transient and manageable.

At week 56, mean blood pressure was generally unchanged from baseline for Contrave patients compared to placebo patients, who tended to experience a slight decrease (approximately 2 mm Hg) from baseline. Contrave treatment did not appear to disrupt the normal circadian pattern of blood pressure. There was a slight increase in pulse (approximately 1 beat per minute) in Contrave patients compared to placebo patients, whose pulse was generally unchanged. There were no meaningful treatment effects on ECGs or laboratory measures including liver function tests. Treatment with Contrave was not associated with increases in symptoms of depression or suicidal ideation and there was no evidence of abuse dependence.

The Company is on track to submit a New Drug Application (NDA) for Contrave with the FDA in the first half of 2010.

About Orexigen® Therapeutics Orexigen Therapeutics, Inc. is a biopharmaceutical company focused on developing therapies that offer multiple approaches to treating obesity. The Company's lead investigational product, Contrave®, has completed the COR clinical development program and is on track for a regulatory submission with the FDA in the first half of 2010. The Company’s second obesity drug candidate, Empatic™ has completed Phase 2 trials. Each product candidate is designed to act on a specific group of neurons in the central nervous system with the goal of achieving appetite suppression and sustained weight loss, through combination therapeutic approaches. Further information about the Company can be found at http://www.Orexigen.com.

Forward-Looking Statements Orexigen cautions you that statements included in this press release that are not a description of historical facts are forward-looking statements. Words such as "believes," "anticipates," "plans," "expects," "indicates," "will," "intends," "potential," "suggests," "assuming," "designed" and similar expressions are intended to identify forward-looking statements. These statements are based on the Company's current beliefs and expectations. These forward-looking statements include statements regarding the efficacy and safety of Empatic™ and Contrave®, the potential for, and timing of, proceeding to Phase 3 clinical trials for Empatic or filing an NDA for Contrave, the commercial and therapeutic potential of Empatic and Contrave, and the potential to obtain regulatory approval for, and effectively treat obesity with, either product candidate. The inclusion of forward-looking statements should not be regarded as a representation by Orexigen that any of its plans will be achieved. Actual results may differ from those set forth in this release due to the risk and uncertainties inherent in the Orexigen business, including, without limitation: additional analyses of data from the Empatic Phase 2B trial or Contrave Phase 3 trials and any other clinical trials of Empatic or Contrave may produce negative or inconclusive results, or may be inconsistent with previously announced results or previously conducted clinical trials; the FDA may not agree with the Company’s interpretation of efficacy and safety results; earlier clinical trials may not be predictive of future results; Empatic or Contrave may not receive regulatory approval on a timely basis or at all, and the FDA may require Orexigen to complete additional clinical, non-clinical or other requirements prior to the submission or the approval of NDAs for either product candidate; the potential for adverse safety findings relating to Empatic or Contrave to delay or prevent regulatory approval or commercialization, or result in product liability claims, including serious adverse events that are not characterized by clinical investigators as possibly related to Empatic or Contrave and adverse events associated with the individual components of these product candidates; the third parties on whom Orexigen relies to assist with the development programs for Empatic or Contrave, including clinical investigators, contract laboratories, clinical research organizations and manufacturing organizations, may not successfully carry out their contractual duties or obligations or meet expected deadlines, and the quality or accuracy of the data or materials generated by such third parties may be of insufficient quality to include in the Company’s regulatory submissions; the ability of Orexigen and its licensors to obtain, maintain and successfully enforce adequate patent and other intellectual property protection of its product candidates; and other risks described in the Company's filings with the Securities and Exchange Commission. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof, and Orexigen undertakes no obligation to revise or update this news release to reflect events or circumstances after the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement. This caution is made under the safe harbor provisions of Section 21E of the Private Securities Litigation Reform Act of 1995. Information included herein is based on the Company’s review and evaluation of the clinical data. All conclusions and determinations contained herein are subject to the Company’s further analysis of the clinical data. The ultimate determination of the safety and efficacy of Contrave and Empatic will be made by the FDA and other relevant regulatory authorities.